Many household appliances, particularly ranges, water heaters and dryers, burn natural gas or liquid petroleum (“LP”) (natural gas and LP will be hereinafter referred to generally as “gas”) to create heat energy. The appliances require a flow regulating valve to control the gas flow from a gas supply to a burner. One such flow regulating valve is a poppet valve.
A poppet valve has a seat that includes a gas passage and a sealing device such as a rubber poppet connected to an actuating arm. The poppet valve functions by selectively moving the rubber poppet toward or away from the seat by selectively actuating the arm connected to the rubber poppet. Particularly, the rubber poppet is moved away from the seat to increase the size of the flow passage or “open” the valve to increase the gas flow rate. The rubber poppet is moved toward the seat to decrease the size of the flow passage or to “close” the valve to decrease or terminate the gas flow rate. The amount of travel by the arm away from the seat determines the distance between the rubber poppet and the seat and the size of the flow passage that is created. To completely stop the gas flow, the rubber poppet is pressed against the seat to completely seal the gas flow passage.
Typically, the arm must be actuated to open the valve. To provide for fail safe operation, the arm is typically spring loaded such that it will automatically close when the arm is not being actuated. This configuration is preferred because if the action mechanism fails it is preferred to have the valve fail in the “closed” position.
The seat is typically a metallic material and the rubber poppet is typically a resilient material such as rubber, plastic or nylon that allows for good sealing contact with the metal seat.
The seat is typically threaded into a metal fitting that is attached to the body of the valve. By being threaded into the fitting, the valve may be adjusted by screwing the seat towards or away from the sealing disc of the poppet. This adjustable configuration is typically referred to as an adjustable seat valve. The metal fitting further includes threads for attaching the gas valve to a gas line having a corresponding fitting.
One problem with the current design of the adjustable seat valve is that when a metal fitting of the gas line is threaded to the metal fitting of the gas valve, the sliding contact between the two fittings forms tiny metal particulates and shavings. Further, when the seat is adjusted, the interaction between the seat and the tool used to adjust the seat may create metal particulates and shavings as well.
To prevent such particulates and shavings from falling into the valve, a wire mesh screen is typically employed above the sealing surface of the valve. Unfortunately, while such a screen is effective to block particles greater than 0.010″, particulates and shavings smaller than this are able to fall through the screen and the gas flow passage of the seat and land on the rubber poppet. Over time, this debris may prematurely deteriorate the sealing disc of the poppet thereby decreasing the seal that can be formed between the rubber poppet and the seat. Particulates from 0.001″ to 0.010″ are identified to cause such leaks. Unfortunately, providing increased filtering of such particulates would unacceptably reduce the BTU flow rate and pressure drop through the valve.
Therefore, a device that would prevent the metal particulate or shavings from falling through the gas flow passage and onto the rubber poppet to prevent deterioration of the seal without unacceptably reducing the BTU flow rate and the pressure drop through the valve would be desirable. The invention provides such a device.